Charging System CB750 Custom

I had a charging problem when I purchased the cb750c it would not
charge the battery,I went thru the troubleshooting guide from
Electrosport and determined it was the rectifier/regulator I replaced
that all was well,about two weeks later its not charging the battery
again any help would be great has anyone had this problem? The
Rectifier/Regulator was brand new from Dennis Kirk...
Battery will accept a charge with no problem,if the battery happened
to be bad would it still show the correct amount of voltage across the
terminals when running 12.8-14.5 if everything else was good?????????

 

Chronic charging system problems lead to a sulfated battery.

Your battery's plates are a lead grid filled with more spongy lead.
The spongy lead allows the electrolyte to penetrate deep inside and
recharge the battery.

If your battery is consistently undercharged, or discharged and
allowed to sit without recharging, a layer of lead sulfate will form
on the plates, keeping the electrolyte from penetrating beneath the
surface of the plate.

The battery will only take a "surface charge", but the voltage will
rise to 14.5 when being charged and the electrolyte specific gravity
will indicate a full state of charge.

But, when you ride the motorcycle, the battery will discharge rapidly.

 

Accepting a charge and being able to HOLD it are two quite different things.

Yes, if you ever see a voltage across the battery higher than 13.5, yet it
is dead the next morning, the odds are excellent that the battery itself is
TOAST.

If you are curious as to why, read Krusty's post.
If not, just get a new battery.

 

You can see 14.5+ volts across the battery terminals when you have
just
disconnected it from the charger.

Then the voltage will settle down to 12.2 to 12.8 volts in the next
half hour.

That doesn't mean the battery has significant load carrying capacity,
though.

 

When the motorcycle is running and I check the battery with a
multimeter it is only registering 11.8 and will not go any higher even
at 5000 rpm I replaced the Regulator/Rectifier 2 weeks ago with a new
one and it was fine registering the right amount of voltage now its
back to discharging do you think it could still be a bad battery or
something worse?
If the battery was bad would it still register the correct amount of
voltage across the terminals while running?
I don't think I was clear in my earlier post about my problem I
apologize i posted right before i went to work this morning and was in
a rush,Thanks to all that have posted I'm leaning toward bad battery
but I wanted to get other opinions..
Thanks
everyone,Larry

 

Wonder if you managed to fry your brand new Regulator/Rectifier.

What does "registering the right amount of voltage" mean ?
Did you see the voltage go up as the engine charged the
battery ?

If the battery will take and hold a charge from a battery charger,
then it's not the battery. If it won't take and hold a charge, then
it is.

There's no one "correct amount of voltage". It should read
at least 12.5 volts with the bike shut off and maybe 14 - 14.5
volts with the engine running fast.

Places that sell batteries should be able and willing to load
test your old battery. Ask them to do this. If the old one's still
good, then you're wasting your time and money by replacing it.

You could also have an alternator or Regulator/Rectifier or
wiring problem. You need to run a systematic troubleshooting
proceedure. Also, be sure to sacrifice at least one chicken
whenever you're troubleshooting any electrical problem.

 

Like I said, the battery could show 14.5 volts after you charge it,
and you can check the electrolyte specific gravity with a hydrometer
or one of those little floating ball gizmos, and everything looks just
fine, but when you turn the ignition switch on and the headlights come
on, the *surface charge* will dissipate immediately and the lights
will go off and nothing will light, not even the neutral light, if the
battery is really sulfated.

OTOH, if you have a trickle charger or a Battery Tender (or even a
wall blob for charging NiCad batteries) you can charge the battery up,
then put it in the bike and turn on the headlights.

A decent battery will keep the headlights lit for 45 minutes or an
hour without the engine running.